Quality Exams

Form 4 Computer Studies KCSE 2024 Predictor

Published on December 12th 2023 | 14 mins , 2686 words

1. Classify the following as input, output or storage device   (5marks) 

a) Keyboard 

  •  input device

b) Microphone 

  •  input device

c) 3D printer 

  •  output device

d) Hard Disk Drive(HDD) 

  •  storage device

e) Sensor 

  • Input device

f) Solid state drive (SSD) 

  • storage device

g) Headphones 

  • output device

h) LCD projector 

  • output device


2. Complete  the following table  (6mks) 

Hexadecimal  12 bit binary   Denary

 028 ------ 

 1A9 ------

 20C .................


3. Parallel data transmission is used in an integrated circuit(IC) 

(a) Describe how data is transmitted using parallel transmission(2mks)

  •  Uses multiple wires 
  • Sends multiple bits of data at a time 

(b) Give one benefit of using parallel, rather than serial , data transmission (1mk) 

  •  Faster transmission speed 

4. The computer has a central processing unit (CPU). 

 (i) Identify the bus that carries the signals around the CPU to control the components (1mk) 

  • Control bus 

(ii) Identify the register built into the Arithmetic and Logic Unit (ALU) (1mk) 

  •  Accumulator(ACC) 

5. Indicate whether the following statements are true or false

Data and instructions are stored in the same memory unit  - True

The control unit manages operations within the CPU -True

Data and instructions can be fetched into the CPU at the same time - False

 The control unit is responsible for decoding an instruction  - True


6. (a) Mathew is buying a new television that uses LED technology. 

Explain what is meant by LED technology 


  • Light emitting diodes (technology) 
  • The display is made up of pixels that are arranged together as a matrix each is formed of three LEDs/filters 
  • Shades of colour are achieved by mixing red, blue and green 
  • The screen can be back-lit/edge-lit 


(b) State three benefits of LED technology. 

  •  Energy efficient // low power consumption 
  • Long lasting // longevity 
  • Focussed beam // less light strays from beam 
  • Brighter/vivid colours 
  • High resolution 
  • No flicker 
  • Display is thinner 
  • Mercury free technology // environmentally friendly 
  • Fewer pixel failure 
  • Increased viewing in sunlight 

7.  Alessandro has some important data stored on his computer. 

He is concerned about accidental damage to his data. 

(a) (i) Identify three ways that the data could be accidentally damaged. 


  • Loss of power/electricity 
  • Spillage of liquids 
  • Flood 
  • Fire 
  • Human error 
  • Hardware failure 
  • Software failure 

(b) State what Alessandro could do to make sure that he can retrieve his data if it is accidentally damaged. 

  • create backup


(c) Alessandro uses an SSD to store his data. 

Describe what is meant by an SSD and how it operates to store data. 

  • Solid state drive 

  • Non-volatile 
  • Secondary storage 
  • Flash memory 
  • Has no mechanical/moving parts 
  • Uses transistor and cells that are laid out in a grid 
  • Uses control gates and floating gates 
  • Can be NAND/NOR (technology) 
  • Use EEPROM technology 

Tina is creating a website for charity events. She uses HTML to create the website. 

(a)    State what is meant by HTML 

Any one from: 

− Hypertext Mark-up Language 

− Web authoring language // language used to write/create websites/web pages 

8. Tina is concerned about security threats to her web server. 

(i) Identify three security threats to her web server that Tina might be concerned about 

  •  Hacking 
  • Denial of service (DoS) attack 
  • Virus 
  • Malware 

ii) Tina installs a proxy server to help protect her website from security threats. 

Describe how the proxy server will help protect the website. 

  • Acts as a firewall 
  • Monitor/filters/examines incoming and outgoing traffic 
  • Rules/criteria for traffic can be set // blacklist/whitelist set 
  • Blocks any traffic that does not meet criteria … 
  • … and can send a warning message to the user 
  • Stop the website failing in a DoS attack // DoS attack hits the proxy server and not the webserver 

9. Identify one other protocol that can be used to secure data transmission over the Internet 




10. Elle uses both CDs and DVDs to store her school projects. 

(a) Give three similarities between a CD and a DVD 



(b) State one difference between a CD and a DVD. 


11. Zakir wants to buy a new laptop. 

(a) He knows that a laptop has both hardware and software. 

Explain why the laptop needs both hardware and software. 




(b) Zakir needs to choose between a solid state drive and a hard disc drive. 

(i) Give two reasons, other than cost and capacity, why Zakir may choose a solid state drive rather than a hard disc drive. 



(ii) Solid state drives store data on flash memory, which is similar to RAM. 

Explain one difference between flash memory and RAM. 


Upeka manages the network in her office building. 

(a) Upeka uses the network to install software updates on all the office computers. 

Give two other reasons why computers are connected in a network 


 (b) The network uses wired and wireless connectivity. 

(i) State two advantages of using wired rather than wireless connectivity. 

(ii) State two disadvantages of using wired rather than wireless connectivity. 


(c) Some people confuse the terms ‘internet’ and ‘World Wide Web’. 

(d)Describe the difference between the internet and the World Wide Web. 

(e) Network layouts can be based upon a number of different network topologies. 

Figure 1 shows a network topology.

Describe two external network threats.

Denial of Service (DOS). A DOS attack overwhelms or locks up resources, preventing access to them

Man-in-the-middle (MitM). A MitM attack is when a bad actor intercepts network traffic and then reads and/or modifies it before sending it on.

 Describe each of the following types of data integrity.

Domain integrity

Domain integrity – requires a given field that only stores a single piece of atomic data and that the data is of the correct data type, and it meets the constraints.

Referential integrity

Referential integrity – requires that foreign keys refer back to a primary key that exists in the parent table. Referential integrity is lost if a foreign key entry has no matching primary key value in the parent table.

Explain how social engineering (phishing) can be used to gain unauthorised access to a network, despite technical security measures being present


Social engineering is when an attacker uses trickery to convince another person to give them information or access to which others should not be privileged. This can be in the form of emails, phone calls or in person. Once the attacker phishes enough information from the victim if limited security is in place, the attacker can gain access to the system through the use of the victim’s credentials. 

State the seven OSI Layers and their roles

Application:  End user application protocols 

Example network component
hardware or protocol



Role : Formatting of data, encryption and decryption

Example : SSL

Session : Manages connections between endpoints 

Example :NetBios

Transport  : Ensures data arrives as expected 

Example :TCP 

Network : Routing packets, determining best path

Example : Routers

Data link : Breaks packets into frames 

 Example : switches 

Physical : Sends data using signals, such as electricity or
visible light 

Example: Cables

Outline the difference between an interpreter and a compiler

A compiler needs to translate the source code into machine code to create an executable
before it can run.

An interpreter translates the source code at the time of execution one line at a time, it does not require the generation of machine code.

Outline the role of a modem.

A modem receives data from a computer hardware device and coverts it from a digital format
to an analog format. Once received it converts the data from analog to digital. This is called modulation and demodulation.

Refer to the partial pseudocode below:
IF a>5 AND a<25
Print a

Describe, with an example, the test data you would use to check this algorithm for accuracy. 

Test data should be used on either side of the statement as well as in the middle.
Need a number below 5, greater than 25 and in the range. To have further accuracy also use the numbers 5 and 25

Explain a difference between the dynamic host configuration protocol (DHCP) and domain name server (DNS).

DNS is an internet service that translates domain names into IP addresses while DHCP is a
protocol that assigns the IP address to the host in a network dynamically through a set range of IP addresses. While a DHCP server sends out information that clients need to communicate with other machines and services, DNS ensures that servers, clients, and services can be found by their names

Outline the role of the following hardware devices in network communications.

A router connects two or more networks or subnetworks. It will read a packet’s header to determine its destination (IP address), then refers to a routing table to determine most efficient route before forwarding the packet to its IP address.

Wireless access point:
Is a wired network device that emits signals for wireless devices to connect and access the network.

This is a network point that allows access to another network that uses different protocols. It acts as a ‘gate’ between the two networks.

Connects multiple wired devices within a network together. A switch receives and forwards
network packets from one device to another on a network.

A network security device that monitors traffic and either allows or blocks data packets based on a set of rules. Can help protect network by filtering traffic and blocking outsiders from gaining unauthorized access to the private data on your computer

A workshop has a lot of heavy machinery operating throughout the day, and requires a cable to connect a workstation to a switch. Which of the following, unshielded twisted pair (UTP) or shielded twisted pair (STP) cable, would be the more suitable? Justify your response

Shielded twisted pair cable:
Twisted pair cable is made up of four pairs of twisted copper wires, a shielded twisted pair cable applies a shield to each one of the pairs on a cable or to all of the pairs together. This shield can reduce EMI (electromagnetic interference), which would be emitted from the
heavy machinery. This increased data transmission quality in the workshop. STP can also reduce crosstalk.

Sarah uses a range of computing devices to complete her studies, including a desktop computer at home, a laptop at school and her mobile phone. Outline two advantages of cloud computing for Sarah.

Sarah could keep all of her files in the cloud and easily access these with her devices. This way she does not have to keep different version on her desktop and laptop.

Flexibility she could access the files from other devices such as the library etc.

Disaster recovery if she accidently dropped or damaged a device – all files would be easy to access

Describe one advantage and one disadvantage of using a pilot implementation for this project.

new system is tried out with a small group of users or on one platform,
allowing for feedback and any changes to be made before making it
available to all customers on all platforms

the old system will still run parallel to the pilot, therefore allowing the pilot
group to revert to the old system should anything go wrong

more cost effective than parallel

less risky than a direct change-over, if the system has flaws it will only
affect a small set of customers

gives some customers/users time to learn how the software works allowing the grocery store time to develop accurate instructions for all other customers

training for employees who need to take the orders can be done gradually.

it will take longer to implement the new system for all customers or for
different platforms

customers using the new platform may become frustrated with the new
system if it does not work as expected – may lose customers.

A programmer has designed a three‑dimensional (3D) interactive computer game. They are going
to develop a program for the game. The program needs to run efficiently, but it must also be developed as soon as possible.
(a)  Identify whether the programmer should use a high‑level language or a
low‑level language to develop the program. Explain the reasons for your choice.

High level programming language


Easier for programmer to read / write / understand / edit herefore, the programmer is less likely to make mistakes // can write
in shorter timeframe

Easier to debug // Easier to find / correct errors so, the programmer can find and correct errors in less time

Game will be machine independent // Game will be portable (between
hardware) i.e  the game can be used on any computer without a need for
understanding of the hardware / compilation for that hardware

Programmer can focus on the problem instead of the manipulation of memory/hardware

Random access memory (RAM) is an example of primary storage.
Give three examples of data that is commonly stored in RAM.

  • Currently running data
  • Currently running (application) software
  • Currently running instructions
  • Currently running parts of OS
  • Currently running utility software

Describe the purpose of secondary storage

  • For non-volatile/permanent/long-term storage of files/data
  • To store data that is not currently required by the CPU
  • To store data to transfer it to another computer

A website allows users to purchase items.
Computer A sends a request for the homepage to the website’s server.
(a) The request is sent using packet switching.
The structure of a packet of data has three elements. One element is the packet header.
(i) Identify two items of data contained in a packet header.

  • Destination IP/address
  • Packet number
  • Originators IP/address
  • Error detection method

(ii) Identify the two other elements of a packet

  • Payload
  • Trailer

Define full‑duplex data transmission.

  • Data goes in both directions at the same time

Two functions of the web browser are to render hypertext markup language (HTML) to display web pages and to store cookies.
Identify two other functions of a web browser

  • Storing bookmarks/favourites
  • Storing history
  • Allow multiple tabs/web pages to be open
  • Allow movement back and forth between web pages // provide navigation tools
  • Allows the user to enter a URL/IP into the address bar
  • Manages HTTP/HTTPS protocol
  • Search cache for IP // Request IP from DNS // Send URL to DNS
  • Sends a request to the IP address/web server (to obtain the contents of a web page)
  • Runs active script / JavaScript / client-side script
  • Allows files to be downloaded from website / internet

(ii) Identify two ways that cookies can be used to enhance the user’s experience of a website.

  • Storing preferences // so the user does not have to select their preferences each time they visit the site
  • Storing account details // so the user does not have to remember / enter
  • their username and password each time they visit the site
  • Storing recent purchases // to allow the user to quickly re-order more items
  • Storing the pages visited/items selected // to display relevant adverts
  • Storing shopping basket // so when the user leaves the site the items are still in their basket

Describe what is meant by robotics

  • The design of robots (to perform tasks/operations/functions)
  • The construction of robots (to perform tasks / operations / functions)
  • The operation of robots (to perform tasks / operations / functions

The robot’s program will use artificial intelligence (AI).
(i) Describe the characteristics of AI.

  • Collects data
  • Stores rules for using the data
  • The ability to reason
  • The ability to learn // uses machine learning by adapting what it does
  • for example, from mistakes to not make them again // result from
  • previous decisions impacts future
  • by changing its own rules by changing its own data by being trained
  • Makes one or more predictions (to make a decision)
  • Find/analyse patterns

A Von Neumann model for a computer system has a central processing unit (CPU) that makes
use of registers.
(a) Identify three registers that may be used.

  • MAR
  • MDR // MBR
  • PC // IAR // NIR // SCR
  • ACC
  • CIR // IR
  • IAS

(b) The CPU is responsible for processing instructions.
One stage of processing instructions is the decode stage.
(i) Identify the two other stages of processing instructions.

  • Fetch
  • Execute

(ii) Identify the component of the CPU that is responsible for decoding instructions

  • Control Unit
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